We have shown previously that epinephrine increases renin secretion from the canine kidney, and that this effect is mediated by an extrarenal event. The present experiments are designed to examine the roles of the liver and adrenal glands in epinephrine-induced renin secretion. An additional goal will be to examine the role of adrenal hormones in the antinatriuretic response to epinhephrine. The role of the liver will be determined by comparing the plasma renin activity (PRA) responses to infusions of epinephrine directly into the hepatic artery with the PRA responses to an identical dose of epinephrine given intravenously (IV) in anesthetized dogs. The role of the adrenal glands will be determined by comparing the PRA response to IV infusion of epinephrine before and after acute adrenalectomy. These experiments are designed to locate the source of the mediator between epinephrine and renin secretion. Since we will be monitoring renal sodium excretion during these experiments as well, the adrenalectomy experiments should provide quantitative information concerning the role of adrenal hormones in epinephrine-induced antinatriuresis.